Fuel dispensing nozzles and devices for recovery of vapor displaced during delivery of fuel, and, in particular, fuel dispensing nozzles having the feature of vapor recovery and/or vapor flow control assemblies for use with such nozzles, are described, e.g., in commonly owned U.S. Pat. Nos. 4,056,131, 4,057,086, 4,343,337, 5,174,346, 5,178,197, 5,327,944 and 6,095,204. The entire disclosures of all of these patents are incorporated herein by reference.
During the process of sequential fueling of a stream of vehicles at a gasoline service station, residual pressure from termination of gasoline flow by the dispenser nozzle at the conclusion of fueling of a first vehicle can result in expansion of the flexible curb hose. When preparing to fuel the next vehicle, if the user lifts the nozzle operating lever while the hose remains pressurized and before the nozzle spout is inserted into the fuel fill pipe, contraction of the flexible hose to relieve internal, residual pressure can cause release or “spitting” of fuel, even if the dispenser has not been authorized for delivery of gasoline.
In Phase II vapor recovery stations equipped with balance vapor recovery nozzles, this problem is absent, since these nozzles have a “no seal/no flow” feature that restricts the operating lever of the nozzle from lifting the fuel valve, thus avoiding spitting. The primary reason for the “no seal/no flow” feature is to insure that the nozzle is in sealing engagement with the vehicle fill pipe before fueling commences, thereby to enhance vapor recovery efficiency. The resulting non-spitting feature of these nozzles is important to the California Air Resources Board (CARB) for protection of self-service customers and for improving air quality. In light of the above, CARB now requires that all vapor recovery nozzles demonstrate the ability to prevent spitting when the nozzle lever is lifted prior to proper insertion of the nozzle spout in a vehicle fill pipe. The CARB test procedure is described in the Phase II regulations under TP-201.2E entitled “Liquid Retention.”